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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>
<A title=alanforsyth@fortune4.fsnet.co.uk
href="mailto:alanforsyth@fortune4.fsnet.co.uk">Alan Forsyth</A> =
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A =
title=pianotech@ptg.org
href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, April 01, 2003 =
5:20
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Dithering =
Hammers</DIV>
<DIV><BR></DIV>
<DIV>A message I tried to send a few weeks ago!<BR><BR><BR>Hi =
guys,<BR>I am
Alan and have been servicing pianos in Edinburgh for the last 10 =
years<BR>with
also a previous short stint in Southern Africa.<BR><BR>I too have been =
baffled
by the problem of dithering hammers in Yamaha<BR>uprights (brand new) =
after
re-regulating the set-off to 1/8". It seems to me<BR>that the factory =
set the
set off wider than usual to accommodate the muffler<BR>rail so that =
the
hammers would not block when the muffler rail was in the<BR>down =
position.
However, with the set-off being 1/4", without the muffler<BR>rail =
(practise
pedal) in use, does not give the piano a very dynamic touch<BR>i.e. =
you cannot
play very loud, and above all you cannot play very soft!<BR>which is =
what
"piano" is. The closer the set-off to the string the more<BR>dynamic =
control
the player has . Set- off is the point at which the jack<BR>disengages =
from
the butt and from then on the player has no control over
the<BR>hammer.<BR><BR>If the set-off is too far away you have less =
control
from the moment of<BR>escapement. Now in most actions if you regulate =
to 1/8"
set-off and even<BR>less in the treble, (I'm talking upright actions =
here) and
all the other<BR>measurements are left standard, the action works =
fine. But on
some actions<BR>this just does not happen as with Yamaha. Playing loud =
is
fine, but as soon<BR>as you play very softly, the hammer =
dithers.<BR>Now this
hammer dither is caused by the butt bouncing off the jack =
before<BR>the hammer
has had a chance to go in to check, and not by the balance =
hammer<BR>bouncing
off the check<BR><BR> You mentioned a design problem, but just =
exactly
where is the design<BR>different from other actions? The only design =
feature I
can think of is that<BR>the length of the jack is too short. In other =
words
there is not enough<BR>leverage on the jack by the set-off button. If =
the jack
were longer, the tip<BR>of the jack would move much faster away from =
the butt
during the aftertouch<BR>motion. The jack must get out of the way =
faster than
the hammer bounces off<BR>the string! So to cure the problem is =
problematic;
one can't obviously<BR>lengthen the jack, but you might be able to =
increase
the leverage on the<BR>jack. I have tried moving the set-off rail =
closer to
the jacks themselves<BR>but this only seems to make a very slight =
difference.
Changing the tension<BR>of the butt springs does not solve the problem =
either.
The only reasonable<BR>solution I have found is to adjust the check =
distance
much closer to the<BR>strings. But then this becomes a non standard
measurement, 1/4" instead of<BR>1/2".<BR><BR>Of course all this begs =
the
question; How softly is a piano supposed to<BR>play? I have had many =
years
experience playing piano in restaurants and<BR>believe me, if there is =
a table
right next to the piano, you have to play<BR>VERY SOFTLY.<BR><BR>I =
sure hope
one of you out there has not just a solution, but the =
correct<BR>solution.
This has been bugging me for years.<BR><BR>Best regards<BR>Alan
=
Forsyth<BR><BR>_______________________________________________<BR>pianote=
ch
list info: <A
=
href="https://www.moypiano.com/resources/#archives">http://www.ptg.org=
/mailman/listinfo/pianotech</A></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV> I don't think you can expect to play quite as =
softly
as a well-regulated grand, but almost. When I used to complain =
about
this to the tech. folks at Yamaha in Buena Park, they would say to
check the same things listed in Carman Gentile's reply, =
including
the pinning, the latter being an item you might not expect to be a =
contributor
to the problem. Any hesitation in the key stroke, which might be =
partly
caused by a tight key bushing, could contribute to the tendency =
to
dither, or "bobble". So you might take the action out, and tap =
with
quick repetition on the rear end of the keys and see that they all =
return with
no sluggishness. Maybe allow the key dip to be slightly larger =
than
normal.</DIV>
<DIV> Regarding let-off, if I'm not mistaken, the =
Yamaha
uprights that have a Disklavier with the "Silent Piano" feature have =
let-off
at almost 1/2" ! Maybe it's only 1/4". I =
first
heard of this at a Disklavier servicing seminar given =
by LaRoy
Edwards at a Yamaha dealer's store. I believe he =
was claiming
that it didn't affect the playablility of the piano all =
that much, which
seems doubtful. I didn't play the piano, but the Disklavier =
mechanism
played it at what I would call a pp level, maybe even =
ppp. So maybe
let-off can be a bit wide. Don't know what else to suggest, =
except call
Yamaha and see if they have anything new on the subject. --David =
Nereson, RPT, Denver<BR></DIV></BLOCKQUOTE></BODY></HTML>